Refrigeration apparatus

ABSTRACT

A refrigeration apparatus includes a heat source unit, a utilization unit, and a liquid refrigerant pipe and gas refrigerant pipe. The utilization unit has utilization unit internal pipelines. The liquid refrigerant pipe and the gas refrigerant pipe connect the heat source unit and the utilization unit internal pipelines. A refrigerant circulates through the heat source unit, the utilization unit, the liquid refrigerant pipe, and the gas refrigerant pipe. The refrigerant contains a compound represented by a molecular formula having one or more carbon-carbon unsaturated bonds. A disproportionation inhibitor for reducing a disproportionation reaction of the refrigerant is applied to at least a part of inner surfaces of the liquid refrigerant pipe, the gas refrigerant pipe, and the utilization unit internal pipelines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending application Ser. No.16/073,440, filed on Jul. 27, 2018, which is the National Phase under 35U.S.C. § 371 of International Application No. PCT/JP2017/002767, filedon Jan. 26, 2017, and under 35 U.S.C. § 119(a) to Patent Application No.2016-016428, filed in Japan on Jan. 29, 2016, all of which are herebyexpressly incorporated by reference into the present application.

TECHNICAL FIELD

The present invention relates to a refrigeration apparatus.

BACKGROUND ART

In recent years, from the viewpoint of reducing global warming, somerefrigeration apparatuses have used hydrofluoroolefin (HFO) as arefrigerant, which is disclosed in Patent Document 1 (JapaneseUnexamined Patent Application Publication No. 2015-007257). HFO iseasily decomposed by OH radicals in the atmosphere, and thus has a lowglobal warming potential. Examples of HFO include1,1,2-trifluoroethylene (HFO-1123) and 2,3,3,3-tetrafluoropropene(HFO-1234yf).

SUMMARY OF THE INVENTION Technical Problem

Some refrigerants used in refrigeration apparatuses tend to undergo aself-decomposition reaction, called a disproportionation reaction, undercertain conditions, because of their low thermal stability. Thedisproportionation reaction is a chemical reaction where two or moremolecules of the same kind are transformed into two or more differentsubstances due to factors, such as a mutual reaction between thesemolecules.

An example of the disproportionation reaction is polymerization ofHFO-1123 refrigerant. HFO-1123 is a compound represented by a molecularformula that has one or more carbon-carbon unsaturated bonds. Because ofthis, a polymerization reaction is more likely to progress at hightemperature and high pressure. The polymerization reaction is a reactionin which plural monomers are polymerized to form a compound (polymercompound) having a large molecular weight. A polymer, which is acompound produced by the polymerization reaction, usually has amolecular weight of 10,000 or more.

Likewise, HFO-1234yf also has a double bond in its composition, andhence is likely to undergo polymerization depending on the conditions,such as high temperature.

If part of the refrigerant is metamorphosed by the disproportionationreaction, the effective amount of the refrigerant circulating in arefrigerant circuit is decreased, causing the degradation in theperformance of the refrigerant circuit. In addition, in some cases,products formed by the disproportionation reaction may clog a pipelinein the refrigerant circuit to inhibit the circulation of therefrigerant.

Therefore, it is an object of the present invention to reduce theoccurrence of a disproportionation reaction of a refrigerant used in arefrigeration apparatus.

Solution to Problem

A refrigeration apparatus according to a first aspect of the presentinvention includes: a heat source unit; a utilization unit; a liquidrefrigerant pipe and a gas refrigerant pipe; and a refrigerant. Theutilization unit has a utilization unit internal pipeline. The liquidrefrigerant pipe and gas refrigerant pipe connect the heat source unitand the utilization unit internal pipeline. The refrigerant circulatesthrough the heat source unit, the utilization unit, the liquidrefrigerant pipe, and the gas refrigerant pipe. The refrigerant containsa compound represented by a molecular formula having one or morecarbon-carbon unsaturated bonds. A disproportionation inhibitor forreducing a disproportionation reaction of the refrigerant is applied toinner surfaces of at least a part of the liquid refrigerant pipe, thegas refrigerant pipe, and the utilization unit internal pipeline.

With this configuration, the disproportionation inhibitor is applied toat least a part of inner surfaces of the liquid refrigerant pipe, thegas refrigerant pipe, and the utilization unit internal pipeline.Therefore, the refrigerant circulating in the refrigerant circuit comesinto contact with the disproportionation inhibitor, so that thedisproportionation reaction is less likely to occur in the refrigerant.

A refrigeration apparatus according to a second aspect of the presentinvention is the refrigeration apparatus according to the first aspect,wherein the disproportionation inhibitor is a polymerization inhibitorfor reducing polymerization of the refrigerant.

With this configuration, the disproportionation inhibitor reduces thepolymerization of the refrigerant. Thus, the degradation in theperformance of the refrigerant circuit due to products of polymerizationcan be reduced.

A refrigeration apparatus according to a third aspect of the presentinvention is the refrigeration apparatus according to the first aspector second aspect, wherein the disproportionation inhibitor contains atleast one of a stabilizer, an antioxidant, or a deoxidant.

With this configuration, the specific composition of thedisproportionation inhibitor is specified.

A refrigeration apparatus according to a fourth aspect of the presentinvention is the refrigeration apparatus according to the third aspect,wherein the disproportionation inhibitor contains the stabilizer. Thestabilizer contains at least one of an oxidation resistance enhancer, aheat resistance improver, or a metal deactivator. The oxidationresistance enhancer and the heat resistance improver contains at leastone of N,N′-diphenyl-phenylenediamine, p-octyldiphenylamine,p,p′-dioctyldiphenylamine, N-phenyl-1-naphthylamine,N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine,di-1-naphthylamine, di-2-naphthylamine, N-alkyl phenothiazine,6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol,4-methyl-2,6-di-(t-butyl)phenol, and4,4′-methylenebis(2,6-di-t-butylphenol). The metal deactivator containsat least one of imidazole, benzimidazole, 2-mercaptobenzthiazole,2,5-dimercaptothiadiazole, salicylidene-propylene diamine, pyrazole,benzotriazole, tolutriazole, 2-methylbenzimidazole,3,5-dimethylpyrazole, methylenebis-benzotriazole, an organic acid or anester thereof, a primary, secondary or tertiary aliphatic amine, anamine salt of an organic acid or inorganic acid, a heterocyclicnitrogen-containing compound, and an amine salt of an alkyl acidphosphate or a derivative thereof.

With this configuration, the specific composition of the stabilizer as acomponent of the disproportionation inhibitor is proposed.

A refrigeration apparatus according to a fifth aspect of the presentinvention is the refrigeration apparatus according to the third orfourth aspect, wherein the disproportionation inhibitor contains theantioxidant. The antioxidant contains at least one of zincdithiophosphate, an organosulfur compound,2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,2,2′-methylenebis(4-methyl-6-tert-butylphenol), phenyl-α-naphthylamine,N,N′-di-phenyl-p-phenylenediamine, andN,N′-disalicilidene-1,2-diaminopropane.

With this configuration, the specific composition of the antioxidant asa component of the disproportionation inhibitor is proposed.

A refrigeration apparatus according to a sixth aspect of the presentinvention is the refrigeration apparatus according to any one of thethird to fifth aspects, wherein the disproportionation inhibitorcontains the deoxidant.

The deoxidant contains at least one of 2-ethylhexyl glycidyl ether,glycidyl phenyl ether, epoxidized cyclohexyl carbinol,di(alkylphenyl)carbodiimide, and β-pinene.

With this configuration, the specific composition of the deoxidant as acomponent of the disproportionation inhibitor is proposed.

Advantageous Effects of Invention

The refrigeration apparatus according to the first aspect of the presentinvention is less likely to cause a disproportionation reaction in therefrigerant.

The refrigeration apparatus according to the second aspect of thepresent invention can reduce the degradation in the performance of arefrigeration circuit due to products of polymerization.

The refrigeration apparatus according to any one of the third to sixthaspects of the present invention specifies the specific compositions ofthe disproportionation inhibitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a refrigerant circuit in arefrigeration apparatus 100 according to an embodiment of the presentinvention; and

FIG. 2 is a schematic diagram showing a utilization unit 20A and arefrigerant communication piping 30 of the refrigeration apparatus 100shown in FIG. 1.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of a refrigeration apparatus according to thepresent invention will be described with reference to the accompanyingdrawings. It should be noted that the specific configuration of therefrigeration apparatus according to the present invention is notlimited to the embodiments below, and various modifications or changescan be made to these embodiments without departing from the scope of thepresent invention.

(1) Overall Configuration

FIG. 1 shows a refrigeration apparatus 100 according to an embodiment ofthe present invention. The refrigeration apparatus 100 is, for example,an air conditioner. The refrigeration apparatus 100 includes a heatsource unit 10, utilization units 20A and 20B, a refrigerantcommunication piping 30, and a refrigerant.

(2) Detailed Configuration (2-1) Heat Source Unit 10

The heat source unit 10 is for generating hot heat or cold heat. Theheat source unit 10 includes a compressor 11, a four-way switching valve12, a heat source unit heat exchanger 13, a heat source unit fan 14, aheat source unit expansion valve 15, a heat source unit liquid passageport 17, a heat source unit gas passage port 18, and heat source unitinternal pipelines 19 a to 19 g.

(2-1-1) Compressor 11

The compressor 11 draws in and compresses a low-pressure gas refrigerantto generate a high-pressure gas refrigerant and then discharges thehigh-pressure gas refrigerant therefrom in the direction indicated bythe arrow.

(2-1-2) Four-Way Switching Valve 12

The four-way switching valve 12 switches between a cold-heat usageoperation and a hot-heat usage operation. The four-way switching valve12 configures a refrigerant path indicated by the solid line during thecold-heat usage operation, and configures a refrigerant path indicatedby the dashed line during the hot-heat usage operation.

(2-1-3) Heat Source Unit Heat Exchanger 13

The heat source unit heat exchanger 13 exchanges heat between therefrigerant and air around the heat source unit 10. In the case of thecold-heat usage operation, the heat source unit heat exchanger 13functions as a condenser and releases the heat from the refrigerant intothe air. On the other hand, in the case of the hot-heat usage operation,the heat source unit heat exchanger 13 functions as an evaporator, andtakes heat from the air into the refrigerant.

(2-1-4) Heat Source Unit Fan 14

The heat source unit fan 14 promotes heat exchange by the heat sourceunit heat exchanger 13.

(2-1-5) Heat Source Unit Expansion Valve 15

The heat source unit expansion valve 15 is a valve capable of adjustingits opening degree, and functions as a decompression device for therefrigerant.

(2-1-6) Accumulator 16

The accumulator 16 is used to cause the gas refrigerant to passtherethrough while accumulating therein the liquid refrigerant that hasnot evaporated at a preceding stage of the compressor 11.

(2-1-7) Heat Source Unit Liquid Passage Port 17

The heat source unit liquid passage port 17 is for connecting a liquidrefrigerant pipe 31. The heat source unit liquid passage port 17incorporates therein a valve for manually closing, when therefrigeration apparatus 100 is not scheduled to be used for a long time,a path through which the liquid refrigerant mainly flows.

(2-1-8) Heat Source Unit Gas Passage Port 18

The heat source unit liquid passage port 17 is for connecting a gasrefrigerant pipe 32. The heat source unit liquid passage port 17incorporates therein a valve for manually closing, when therefrigeration apparatus 100 is not scheduled to be used for a long time,a path through which the gas refrigerant mainly flows.

(2-1-9) Heat Source Unit Internal Pipelines 19 a to 19 g

The heat source unit internal pipelines 19 a to 19 g are pipelines thatconnect a plurality of constituent elements of the heat source unit 10,that is, the compressor 11, the four-way switching valve 12, the heatsource unit heat exchanger 13, the heat source unit expansion valve 15,the heat source unit liquid passage port 17, and the heat source unitgas passage port 18, and contribute to transfer of the refrigeranttherebetween.

(2-2) Utilization Units 20A and 20B

The utilization units 20A and 20B are to utilize the hot heat or coldheat generated by the heat source unit 10 for convenience of users. Theutilization unit 20A includes a utilization unit expansion valve 21, autilization unit heat exchanger 22, a utilization unit fan 23, autilization unit liquid passage port 27, a utilization unit gas passageport 28, and utilization unit internal pipelines 29 a to 29 c. Theconfiguration of the utilization unit 20B is also the same as theconfiguration of the utilization unit 20A.

Hereinafter, the detailed configuration of the utilization unit 20A willbe described, and a description of the configuration of the utilizationunit 20B will be omitted.

(2-2-1) Utilization Unit Expansion Valve 21

The utilization unit expansion valve 21 is a valve capable of adjustingits opening degree, and functions as a decompression device or flow rateadjustment device for the gas refrigerant.

(2-2-2) Utilization Unit Heat Exchanger 22

The utilization unit heat exchanger 22 exchanges heat between therefrigerant and the air around the utilization unit 20A. In the case ofthe cold-heat usage operation, the utilization unit heat exchanger 22functions as an evaporator and takes heat from the air into therefrigerant. On the other hand, in the case of the hot-heat usageoperation, the utilization unit heat exchanger 22 functions as acondenser and releases the heat from the refrigerant into the air.

(2-2-3) Utilization Unit Fan 23

The utilization unit fan 23 promotes heat exchange by the utilizationunit heat exchanger 22.

(2-2-4) Utilization Unit Liquid Passage Port 27

The utilization unit liquid passage port 27 is a portion for connectinga liquid refrigerant pipe 31.

(2-2-5) Utilization Unit Gas Passage Port 28

The utilization unit gas passage port 28 is a portion for connecting agas refrigerant pipe 32.

(2-2-6) Utilization Unit Internal Pipelines 29 a to 29 c

The utilization unit internal pipelines 29 a to 29 c are pipelines thatconnect a plurality of constituent elements of the utilization unit 20A,that is, the utilization unit expansion valve 21, the utilization unitheat exchanger 22, the utilization unit liquid passage port 27, and theutilization unit gas passage port 28, and contribute to transfer of therefrigerant therebetween.

(2-3) Refrigerant Communication Piping 30

The refrigerant communication piping 30 connects the heat source unit 10and the utilization unit 20A to form a refrigerant circuit. Therefrigerant communication piping 30 has a liquid refrigerant pipe 31 anda gas refrigerant pipe 32. The liquid refrigerant pipe 31 connects theheat source unit liquid passage port 17 and the utilization unit liquidpassage port 27. The gas refrigerant pipe 32 connects the heat sourceunit gas passage port 18 and the utilization unit gas passage port 28.

(2-4) Refrigerant

The refrigerant circulates through the heat source unit 10, theutilization units 20A and 20B, and the refrigerant communication piping30. The refrigerant contains a compound represented by a molecularformula that has one or more carbon-carbon unsaturated bonds. Therefrigerant is, for example, HFO.

(2-5) Disproportionation Inhibitor 40

FIG. 2 shows the utilization unit 20A and the refrigerant communicationpiping 30 of the refrigeration apparatus 100. A disproportionationinhibitor 40 is applied to inner surfaces of at least a part of theliquid refrigerant pipe 31, the gas refrigerant pipe 32, and theutilization unit internal pipelines 29 a to 29 c. The disproportionationinhibitor 40 is a substance for reducing the occurrence or progress ofthe disproportionation reaction. Preferably, the disproportionationinhibitor 40 is a polymerization inhibitor that reduces polymerizationof the refrigerant.

The disproportionation inhibitor 40 contains at least one of astabilizer, an antioxidant, or a deoxidant.

(2-5-1) Stabilizer

The stabilizer contains at least one of an oxidation resistanceenhancer, a heat resistance improver, or a metal deactivator.

The oxidation resistance enhancer and the heat resistance improvercontain at least one of the substances listed below.

<Oxidation Resistance Enhancer, Heat Resistance Improver>

N,N′-diphenyl-phenylenediamine, p-octyldiphenylamine,p,p′-dioctyldiphenylamine, N-phenyl-1-naphthylamine,N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine,di-1-naphthylamine, di-2-naphthylamine, N-alkyl phenothiazines,6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol,4-methyl-2,6-di-(t-butyl)phenol, and4,4′-methylenebis(2,6-di-t-butylphenol).

The metal deactivator contains at least one of the substances listedbelow.

<Metal Deactivator>

Imidazole, benzimidazole, 2-mercaptobenzthiazole,2,5-dimercaptothiadiazole, salicylidene-propylenediamine, pyrazole,benzotriazole, tolutriazole, 2-methylbenzimidazole,3,5-dimethylpyrazole, methylenebis-benzotriazole, organic acids or theiresters, primary, secondary or tertiary aliphatic amines, amine salts ofan organic acid or inorganic acid, nitrogen-containing heterocycliccompounds, and amine salts of alkyl acid phosphates or theirderivatives.

(2-5-2) Antioxidant

The antioxidant contains at least one of the substances listed below.

<Antioxidant>

Zinc dithiophosphates, organosulfur compounds,2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,2,2′-methylenebis(4-methyl-6-tert-butylphenol), phenyl-α-naphthylamine,N,N′-di-phenyl-p-phenylenediamine, andN,N-disalicilidene-1,2-diaminopropane.

(2-5-3) Deoxidant

The deoxidant contains at least one of the substances listed below.

<Deoxidant>

2-ethylhexyl glycidyl ether, phenyl glycidyl ether, epoxidizedcyclohexyl carbinol, di(alkylphenyl)carbodiimides, and β-pinene.

(3) Basic Operation (3-1) Cold-Heat Operation

In the cold-heat operation, the four-way switching valve 12 configures arefrigerant path indicated by the solid line in FIG. 1. The compressor11 discharges the high-pressure gas refrigerant in the directionindicated by the arrow in FIG. 1. After passing through the four-wayswitching valve 12, the high-pressure gas refrigerant reaches the heatsource unit heat exchanger 13. The heat source unit heat exchanger 13functions as a condenser, and converts the high-pressure gas refrigerantinto a high-pressure liquid refrigerant. The high-pressure liquidrefrigerant is decompressed in the heat source unit expansion valve 15,the liquid refrigerant pipe 31, and the utilization unit expansion valve21 to become a gas-liquid two-phase refrigerant, which then reaches theutilization unit heat exchanger 22. The utilization unit heat exchanger22 functions as an evaporator and absorbs heat from the ambient air in aprocess of converting the gas-liquid two-phase refrigerant into alow-pressure gas refrigerant, thereby cooling the ambient air. Thelow-pressure gas refrigerant passes through the gas refrigerant pipe 32and then through the four-way switching valve 12, and is then drawn intothe compressor 11 via the accumulator 16.

(3-2) Hot-Heat Operation

In the hot-heat operation, the four-way switching valve 12 configures arefrigerant path indicated by the dashed line in FIG. 1. The compressor11 discharges the high-pressure gas refrigerant in the directionindicated by the arrow in FIG. 1. After passing through the four-wayswitching valve 12 and then through the gas refrigerant pipe 32, thehigh-pressure gas refrigerant reaches the utilization unit heatexchanger 22. The utilization unit heat exchanger 22 functions as acondenser, and dissipates heat in a process of converting thehigh-pressure gas refrigerant into a high-pressure liquid refrigerant,thereby warming the ambient air. The high-pressure liquid refrigerant isdecompressed in the utilization unit expansion valve 21, the liquidrefrigerant pipe 31, and the heat source unit expansion valve 15 tobecome a gas-liquid two-phase refrigerant, which then reaches the heatsource unit heat exchanger 13. The heat source unit heat exchanger 13functions as an evaporator, and converts the gas-liquid two-phaserefrigerant into a low-pressure gas refrigerant. Thereafter, thelow-pressure gas refrigerant passes through the four-way switching valve12 and is then drawn into the compressor 11 via the accumulator 16.

(4) Installation Procedure

When the refrigeration apparatus 100 is installed, the heat source unit10 is installed outdoors, while the utilization units 20A and 20B areinstalled indoors. In this installation procedure, the heat source unit10 includes a liquid refrigerant sealed therein in advance in an amountrequired by the entire refrigeration apparatus 100. Then, therefrigerant communication piping 30 is installed for connecting the heatsource unit 10 to each of the utilization units 20A and 20B, therebycompleting the refrigerant circuit of the refrigeration apparatus 100.Finally, the refrigerant enclosed in the heat source unit 10 is releasedto the refrigerant circuit, and then flows toward the utilization units20A and 20B. At this time, when the disproportionation inhibitor 40 isapplied to the inner surface of the liquid refrigerant pipe 31 or thegas refrigerant pipe 32, the refrigerant comes into contact with thedisproportionation inhibitor 40. Therefore, the disproportionationreaction is less likely to occur in the refrigerant passing through theliquid refrigerant pipe 31 or the gas refrigerant pipe 32. Then, therefrigerant that has reached the utilization unit liquid passage port 27and the utilization unit gas passage port 28 penetrates into eachportion of the utilization unit 20A. At this time, when thedisproportionation inhibitor 40 is applied to the inner surfaces of theutilization unit internal pipelines 29 a to 29 c, the refrigerant comesinto contact with the disproportionation inhibitor 40. Therefore, thedisproportionation reaction is less likely to occur in the refrigerantpassing through the utilization unit internal pipelines 29 a to 29 c.

(5) Features

(5-1)

The disproportionation inhibitor 40 is applied to inner surfaces of atleast a part of the liquid refrigerant pipe 31, the gas refrigerant pipe32, and the utilization unit internal pipelines 29 a to 29 c. Therefore,the refrigerant circulating in the refrigerant circuit comes intocontact with the disproportionation inhibitor 40, so that thedisproportionation reaction of the refrigerant is less likely to occur.

(5-2)

The disproportionation inhibitor 40 may be a polymerization inhibitorthat reduces polymerization of the refrigerant. With this configuration,the disproportionation inhibitor 40 reduces the polymerization of therefrigerant. Thus, the degradation in the performance of the refrigerantcircuit due to products of polymerization can be reduced.

(5-3)

The present application has shown various findings regarding thecomposition of the disproportionation inhibitor 40. That is, thedisproportionation inhibitor 40 may include at least one of astabilizer, an antioxidant, or the deoxidant. The stabilizer may containat least one of an oxidation resistance enhancer, a heat resistanceimprover, and a metal deactivator. In addition, possible compositions ofeach of the oxidation resistance enhancer, the heat resistance improver,the metal deactivator, the antioxidant, and the deoxidant are describedin the paragraph (2-4) herein. According to these findings, the specificpossible compositions of the disproportionation inhibitor 40 arepresented, thus enabling the manufacture and preparation thereof.

(6) Modified Examples (6-1) Configuration

In the above embodiment, the refrigerant used in the refrigerationapparatus 100 contains the compound represented by the molecular formulathat has one or more carbon-carbon unsaturated bonds. Instead of this,specifically, the refrigerant may be a mixed refrigerant that containsHFO and HFC as main components. Further, refrigerant oil used in therefrigeration apparatus 100 may be a refrigerant oil that contains analkyl aromatic hydrocarbon and an oxygen-containing hydrocarbon as maincomponents.

HFO is hydrofluoroolefin. HFO is a compound represented by the molecularformula having one or more carbon-carbon unsaturated bonds. Examples ofHFO include 1,1,2-trifluoroethylene (HFO-1123), and2,3,3,3-tetrafluoropropene (HFO-1234yf). HFO is easily decomposed by OHradicals in the atmosphere, and thus has a low global warming potential.

HFC is hydrofluorocarbon. Examples of HFC include R134a represented by amolecular formula C₂H₂F₄, R32 represented by a molecular formula CH₂F₂,and mixed refrigerants R410A and R407c. HFC does not contain chlorineand thus is less effective in destroying an ozone layer thanchlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC).

The alkyl aromatic hydrocarbon is a compound formed by bonding an alkylgroup to an aromatic hydrocarbon, such as benzene or naphthalene. Thealkyl aromatic hydrocarbon is, for example, an alkylbenzene, such astoluene and ethylbenzene.

The oxygen-containing hydrocarbon includes an ester compound, an ethercompound, or a mixture of an ester compound and an ether compound.Examples of the oxygen-containing hydrocarbons include polyvinyl ethersand polyol esters.

The refrigeration apparatus shows the following tendencies regarding theHFO refrigerant ratio, which is a mixing ratio of HFO in a mixedrefrigerant (in terms of weight ratio; the same shall applyhereinafter); the HFC refrigerant ratio, which is a mixing ratio of HFCin a mixed refrigerant; an alkyl aromatic oil ratio, which is the mixingratio of the alkyl aromatic hydrocarbon in the refrigerant oil; and theoxygen-containing oil ratio, which is the mixing ratio of theoxygen-containing hydrocarbon in the refrigerant oil.

Specifically, in the case of using a mixed refrigerant in which the HFOrefrigerant ratio is larger than the HFC refrigerant ratio, arefrigerant oil in which the alkyl aromatic oil ratio is larger than theoxygen-containing oil ratio is used. Conversely, in the case of using amixed refrigerant in which the HFO refrigerant ratio is smaller than theHFC refrigerant ratio, a refrigerant oil in which the alkyl aromatic oilratio is smaller than the oxygen-containing oil ratio is used. Forexample, when the HFO refrigerant ratio is 70% and the HFC refrigerantratio is 30%, the alkyl aromatic oil ratio is 80% and theoxygen-containing oil ratio is 20%. Note that the HFO refrigerant ratiois preferably equal to the alkyl aromatic oil ratio, and the HFCrefrigerant ratio is preferably equal to the oxygen-containing oilratio. Furthermore, preferably, the HFO refrigerant ratio is 40 to 60%,the HFC refrigerant ratio is 60 to 40%, the alkyl aromatic oil ratio is40 to 60%, and the oxygen-containing oil ratio is 60 to 40%. Forexample, when the HFO refrigerant ratio is 40% and the HFC refrigerantratio is 60%, preferably, the alkyl aromatic oil ratio is 40% and theoxygen-containing oil ratio is 60%.

This refrigeration apparatus uses a mixed refrigerant of HFO and HFC asa refrigerant having a low global warming potential. HFO, such asHFO1123, has a carbon-carbon unsaturated bond, and thus can undergo apolymerization reaction in a high-temperature atmosphere, such as theinterior space of a compressor. When R32 is used as the HFC, an ethercompound and an ester compound are preferably used as the refrigerantoil that has good compatibility with the refrigerant. However, the ethercompounds and ester compounds function as initiators of thepolymerization reaction of HFO having a carbon-carbon unsaturated bond.A polymer produced by the polymerization reaction of HFO adheres topipes or the like of the refrigeration apparatus, causing clogging of arefrigerant flow passage.

However, by adding a predetermined amount of an alkyl aromatichydrocarbon, which is less likely to function as an initiator of thepolymerization reaction, as a main component of the refrigerant oil, thepolymerization reaction of HFO can be reduced while securing thecompatibility between HFC and the refrigerant oil. Thus, it ispreferable that as the HFO refrigerant ratio, which is the mixing ratioof HFO in the mixed refrigerant, becomes higher, the alkyl aromatic oilratio, which is the mixing ratio of alkyl aromatic hydrocarbons in therefrigerant oil, is high.

(6-2) Features (6-2-1) First Aspect of Modified Example

The refrigeration apparatus 100 according to a first aspect of amodified example uses: a mixed refrigerant that contains HFO and HFC asmain components; and a refrigerant oil that contains an alkyl aromatichydrocarbon and an oxygen-containing hydrocarbon as main components. Theoxygen-containing hydrocarbon contains at least one of an ether or anester. In the mixed refrigerant, the weight mixing ratio of HFO isdefined as a first refrigerant ratio, and the weight mixing ratio of HFCis a second refrigerant ratio. In the refrigerant oil, the mixing ratioof the alkyl aromatic hydrocarbon is a first oil ratio, and the mixingratio of the oxygen-containing hydrocarbon is a second oil ratio. Whenthe first refrigerant ratio is greater than the second refrigerantratio, the first oil ratio is greater than the second oil ratio. Whenthe first refrigerant ratio is smaller than the second refrigerantratio, the first oil ratio is smaller than the second oil ratio.

With this configuration, the refrigerant oil contains the alkyl aromatichydrocarbon. HFO refrigerants have carbon-carbon unsaturated bonds, andsome of the HFO refrigerants, such as HFO1123, are easily polymerized athigh temperatures. Meanwhile, the ether compound and the ester compoundare suitable for use as the refrigerant oil having good compatibilitywith the HFC refrigerant, such as R32. However, ether compounds andester compounds tend to function as initiators for the polymerizationreaction of the HFO refrigerant having a carbon-carbon unsaturated bond.The polymer produced by the polymerization reaction adheres to pipes orthe like of the refrigeration apparatus, causing clogging of therefrigerant flow passage. However, by adding a predetermined amount ofthe alkyl aromatic hydrocarbon as a main component of the refrigerantoil, the polymerization reaction of the HFO refrigerant can be reducedwhile ensuring the compatibility between the HFC refrigerant and therefrigerant oil. Therefore, according to the first aspect, therefrigeration apparatus can be provided which has high safety whilereducing clogging of the polymer generated by the polymerizationreaction of the refrigerant.

(6-2-2) Second Aspect of Modified Example

A refrigeration apparatus 100 according to a second aspect of a modifiedexample is the refrigeration apparatus according to the first aspect ofthe modified example wherein HFO1123 may be used as HFO, and R32 may beused as HFC.

With this configuration, by adding a predetermined amount of the alkylaromatic hydrocarbon as a main component of the refrigerant oil, thepolymerization reaction of the HFO1123, which is a kind of the HFOrefrigerant, can be reduced while ensuring the compatibility with R32,which is a kind of the HFC refrigerant.

(6-2-3) Third Aspect of Modified Example

A refrigeration apparatus 100 according to a third aspect of a modifiedexample is the refrigeration apparatus according to the first aspect orthe second aspect of the modified example wherein the first refrigerantratio is equal to the first oil ratio, and the second refrigerant ratiois equal to the second oil ratio.

With this configuration, by adding a predetermined amount of the alkylaromatic hydrocarbon as a main component of the refrigerant oil, thepolymerization reaction of the HFO refrigerant can be reduced whileensuring the compatibility with the HFC refrigerant.

(6-2-4) Fourth Aspect of Modified Example

A refrigeration apparatus 100 according to a fourth aspect of a modifiedexample is the refrigeration apparatus according to any one of the firstto third aspects of the modified example wherein the first refrigerantratio is 40% to 60%, the second refrigerant ratio is 60% to 40%, thefirst oil ratio is 40% to 60%, and the second oil ratio is 60% to 40%.

With this configuration, the polymerization reaction of the HFOrefrigerant can be more reduced while ensuring the compatibility betweenthe HFC refrigerant and the refrigerant oil.

REFERENCE SIGNS LIST

10 Heat source unit19 a to g Heat source unit internal pipeline20A, 20B Utilization unit29 a to c Utilization unit internal pipeline30 Refrigerant communication pipe31 Liquid refrigerant pipe32 Gas refrigerant pipe40 Disproportionation inhibitor

100 Refrigerator CITATION LIST Patent Literature

Japanese Unexamined Patent Application Publication No. 2015-007257

1. A refrigeration apparatus comprising: a refrigerant pipe; a heatexchanger connected to the refrigerant pipe; a compressor connected tothe refrigerant pipe; a refrigerant containing HFO and HFC as maincomponents, the refrigerant passing through the refrigerant pipe, arefrigerant oil containing an alkyl aromatic hydrocarbon and anoxygen-containing hydrocarbon as main components; the oxygen-containinghydrocarbon including at least one of an ester and an ether, a firstrefrigerant ratio being a mixing ratio by weight of HFO in therefrigerant, a second refrigerant ratio being a mixing ratio by weightof HFC in the refrigerant, a first oil ratio being a mixing ratio of thealkyl aromatic hydrocarbon in the refrigerant oil, a second oil ratiobeing a mixing ratio of the oxygen-containing hydrocarbon in therefrigerant oil, wherein the first oil ratio is larger than the secondoil ratio in a case where the first refrigerant ratio is larger than thesecond refrigerant ratio, whereas the first oil ratio is smaller thanthe second ratio in a case where the first refrigerant ratio is smallerthan the second refrigerant ratio.
 2. The refrigeration apparatusaccording to claim 1, wherein the HFO is HFO1123, and wherein the HFC isR32.
 3. The refrigeration apparatus according to claim 1, wherein thefirst refrigerant ratio is equal to the first oil ratio, and wherein thesecond refrigerant ratio is equal to the second oil ratio.
 4. Therefrigeration apparatus according to claim 1, wherein the firstrefrigerant ratio is 40 to 60%, wherein the second refrigerant ratio is60 to 40%, wherein the first oil ratio is 40 to 60%, and wherein thesecond ratio is 60 to 40%.
 5. The refrigeration apparatus according toclaim 1, further comprising a polymerization inhibitor for reducingpolymerization of the refrigerant, the polymerization inhibitor providedin the refrigerant pipe.
 6. The refrigeration apparatus according toclaim 1, further comprising at least one of an oxidation resistanceenhancer, a heat resistance improver, and a metal deactivator, providedin the refrigerant pipe, wherein the oxidation resistance enhancer andthe heat resistance improver contains at least one ofN,N′-diphenyl-phenylenediamine, p-octyldiphenylamine,p,p′-dioctyldiphenylamine, N-phenyl-1-naphthylamine,N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine,di-1-naphthylamine, di-2-naphthylamine, N-alkyl phenothiazine,6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol,4-methyl-2,6-di-(t-butyl)phenol, and4,4′-methylenebis(2,6-di-t-butylphenol), and the metal deactivatorcontains at least one of imidazole, benzimidazole,2-mercaptobenzthiazole, 2,5-dimercaptothiadiazole,salicylidene-propylene diamine, pyrazole, benzotriazole, tolutriazole,2-methylbenzimidazole, 3,5-dimethylpyrazole, methylenebis-benzotriazole,an organic acid or an ester thereof, a primary, secondary or tertiaryaliphatic amine, an amine salt of an organic acid or inorganic acid, aheterocyclic nitrogen-containing compound, and an amine salt of an alkylacid phosphate or a derivative thereof.
 7. The refrigeration apparatusaccording to claim 1, further comprising an antioxidant provided in therefrigerant pipe, wherein the antioxidant contains at least one of zincdithiophosphate, an organosulfur compound,2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,2,2′-methylenebis(4-methyl-6-tert-butylphenol), phenyl-α-naphthylamine,N,N′-di-phenyl-p-phenylenediamine, andN,N′-disalicilidene-1,2-diaminopropane.
 8. The refrigeration apparatusaccording to claim 1, further comprising a deoxidant provided in therefrigerant pipe, wherein the deoxidant contains at least one of2-ethylhexyl glycidyl ether, glycidyl phenyl ether, epoxidizedcyclohexyl carbinol, di(alkylphenyl)carbodiimide, and β-pinene.
 9. Arefrigeration apparatus comprising: a refrigerant pipe; a heat exchangerconnected to the refrigerant pipe; a compressor connected to therefrigerant pipe; a refrigerant containing HFO and HFC as maincomponents, the refrigerant passing through the refrigerant pipe, arefrigerant oil containing an alkyl aromatic hydrocarbon and anoxygen-containing hydrocarbon as main components; the oxygen-containinghydrocarbon including at least one of an ester and an ether, a firstrefrigerant ratio being a mixing ratio by weight of HFO in therefrigerant, a second refrigerant ratio being a mixing ratio by weightof HFC in the refrigerant, a first oil ratio being a mixing ratio of thealkyl aromatic hydrocarbon in the refrigerant oil, a second oil ratiobeing a mixing ratio of the oxygen-containing hydrocarbon in therefrigerant oil, wherein the first oil ratio is larger than the secondoil ratio, and the first refrigerant ratio is larger than the secondrefrigerant ratio.
 10. A refrigeration apparatus comprising: arefrigerant pipe; a heat exchanger connected to the refrigerant pipe; acompressor connected to the refrigerant pipe; a refrigerant containingHFO and HFC as main components, the refrigerant passing through therefrigerant pipe, a refrigerant oil containing an alkyl aromatichydrocarbon and an oxygen-containing hydrocarbon as main components; theoxygen-containing hydrocarbon including at least one of an ester and anether, a first refrigerant ratio being a mixing ratio by weight of HFOin the refrigerant, a second refrigerant ratio being a mixing ratio byweight of HFC in the refrigerant, a first oil ratio being a mixing ratioof the alkyl aromatic hydrocarbon in the refrigerant oil, a second oilratio being a mixing ratio of the oxygen-containing hydrocarbon in therefrigerant oil, wherein the first oil ratio is smaller than the secondratio, and the first refrigerant ratio is smaller than the secondrefrigerant ratio.